wlrange: Find the overlapping wavelength range in a list of spectra

Package: rvsao

Usage

wlrange spectra

Parameters

spectra = "": List of file names of spectra to analyze. @<filename> indicates list should come from file <filename>. <filename>[<range>] indicates that a range of apertures in a multispec file should be processed, where <range> is a comma- and/or hyphen-separated list of numbers.

specnum = 0: If this is nonzero and spectra contains a single file name, this is a range of spectrum numbers in a multispec file which will be added. Wavelength dispersion information is read from APNUMn or the WCS keywords. Velocity information is read from APVELn and saved in APVELn and APVXCn. In a non-multispec file, radial velocity is read from the VELOCITY header parameter.

specband = 0: If this is nonzero, it is the band in the multispec file(s) specified by spectra which will be summed. Wavelength dispersion information is read from APNUMn, where n is the aperture specified by specnum or the WCS keywords. Velocity information is read from APVELn and saved in APVELn and APVXCn. (New in version 2.0)

specdir = "./": Directory containing spectra to analyze. This part of the pathname is not printed at the top of the page, and is assumed to be the same for all spectra listed in the spectra parameter.

st_lambda = INDEF: Starting wavelength in angstroms of output spectrum. If INDEF, use beginning of wavelength overlap between input spectra.

end_lambda = INDEF: Ending wavelength in angstroms of output spectrum. If INDEF, use end of wavelength overlap between input spectra.

pix_lambda = INDEF: Wavelength per pixel in angstroms of output spectrum. If INDEF, compute from wavelength range and number of pixels in output spectra.

ncol = INDEF: Number of pixels into which to rebin data.

wl1 = INDEF: Reddest wavelength in Angstroms (returned)

wl2 = INDEF: Bluest wavelength in Angstroms (returned)

dwl = INDEF: Wavelength per pixel in Angstroms (returned)

npix = INDEF: Number of pixels (from file or set) (returned)

velcomp = INDEF: Velocity in km/sec to which to shift individual spectra. If INDEF, do not shift spectra at all.

zcomp = INDEF: Velocity of output spectrum as delta lambda / lambda; overrides velcomp if not INDEF.

svel_corr = "barycentric": Spectrum velocity correction to the solar system barycenter. Set to "none" if spectrum has already been shifted or if this correction is unnecessary. If "file", BCV is used if present in the file header, or else HCV. If "hfile", the header parameter HCV is always used. If neither is found, no correction is made. If svel_corr is not set to "none", but velcomp and zcomp are INDEF, data is shifted to the barycentric velocity correction of the first spectrum, if it has one. If "heliocentric" or "barycentric" corrections are chosen, position and time parameters are read from the spectrum data file header. DATE-OBS (date in format 'dd-mm-yy') UT (U.T. at end of exposure as 'hh:mm:ss') and UTOPEN (U.T. at start of exposure as 'hh:mm:ss') or EXPOSURE (length of exposure in seconds) are used to compute the midtime of the exposure. RA (right ascension as 'hh:mm:ss.ss'), DEC (declination as 'dd:mm:ss.ss'), and EPOCH (epoch of coordinates defaults to 1950.0) give the position of the object whose spectrum this is. SITELONG (observatory longitude as 'dd:mm:ss.ss' or degrees), SITELAT (observatory latitude as 'dd:mm:ss.ss' or degrees), and SITEELEV (observatory altitude in meters) give the observatory position. Use bcvcorr task to set BCV in header and use "file" here if header parameters are different.

nsum = 1: Number of pixels to sum across dispersion

verbose = yes: Display final result (yes or no)

debug = no: Display intermediate results (yes or no)

Description

WLRANGE reads a list of spectra, shifting them to a common redshift, if either the vel_comp or the z_comp parameter is not INDEF. The VELOCITY header parameter of each of these spectra is assumed to be a solar-system-barycenter-corrected velocity, and a barycentric correction (computed by SUMSPEC or extracted from the BCV or HCV header parameter) is subracted to get the redshift of the spectrum.

The wavelength overlap blue and red limits are returned as well as the maximum number of pixels per spectrum and a wavelength per pixel binning which would match that number to the range.

Example

Get the overlapping wavelength range for a 300-fiber Hectospec spectrum:

rvsao> wlrange comp.ms.fits WLRANGE: 4608-point spectra from 3550.852A to 6040.839A by 0.540A rvsao> dpar wlrange wlrange.spectra = "comp.ms.fits[1-300]" wlrange.specnum = "0" wlrange.specband = 0 wlrange.specdir = "" wlrange.st_lambda = INDEF wlrange.end_lambda = INDEF wlrange.pix_lambda = INDEF wlrange.npts = INDEF wlrange.wl1 = 3550.8524067942 wlrange.wl2 = 6040.838948816 wlrange.dwl = 0.54047895420487 wlrange.npix = 4608 wlrange.velcomp = INDEF wlrange.zcomp = INDEF wlrange.svel_corr = "none" wlrange.nsum = 1 wlrange.verbose = yes wlrange.debug = no wlrange.mode = "ql" # EOF

wlrange: Find the overlapping wavelength range in a list of spectra

Usage

Parameters

Description

Example

See also